Field of the Invention
The present invention relates to a technique that allows an information processing apparatus operable in a power saving mode to reduce a time required until an operation unit becomes operable when the information processing apparatus returns from the power saving mode.
Description of the Related Art
Conventionally, a multifunction peripheral, which is provided with a scanning function, a printing function, a facsimile function, a document transmission function, and the like, has included an operation unit for displaying an operation screen. A main central processing unit (CPU) of the multifunction peripheral is in charge of main control of the operation unit.
Such a multifunction peripheral shifts to a power saving mode under a certain condition to reduce power consumption. In the power saving mode, the multifunction peripheral stops power supply to the operation unit and respective devices such as a scanner and a printer. Then, upon detecting a factor for returning from the power saving mode (for example, when a switch on the operation unit is pressed), the multifunction peripheral starts power supply to the devices that have been out of operation.
A return from the power saving mode requires a certain time until an initial screen is displayed on the operation unit, because the main CPU performs startup processing on the respective devices. For example, the main CPU performs the startup processing on the devices that have been out of operation, and checks the statuses of the respective devices in the multifunction peripheral when the multifunction peripheral returns from the power saving mode. As a result, processing loads are concentrated on the main CPU during the return from the power saving mode. Because the main CPU displays the screen on the operation unit after completing this startup processing, a user is kept waiting until the initial screen is displayed.
Therefore, an image processing apparatus discussed in Japanese Patent Application Laid-Open No. 2003-141501 employs a configuration in which, when it is difficult for a main CPU to directly control drawing on a liquid crystal display (LCD) of an operation unit, a sub CPU, which operates independently from an operation state of the main CPU, directly draws an initial screen on the operation unit.
However, although the configuration discussed in Japanese Patent Application Laid-Open No. 2003-141501 allows the initial screen to be quickly displayed on the operation unit when the image processing apparatus returns from the power saving mode, the image processing apparatus cannot receive a user's operation via the initial screen until the main CPU completes the startup processing.